1. Field of the Invention
The present invention relates to a differential drive circuit and a communication device which process a differential signal propagated on a differential transmission line or the like.
2. Description of the Related Art
Differential signals are widely used for long-distance transmission of data at high speed.
In particular, the push-pull driver described in Japanese Unexamined Patent Application Publication No. 2006-345259 is frequently used because the current necessary for driving a differential signal to the load is small.
In this type of circuit, the average voltage across the load does not stabilize unless the average values of a pull-up current and a pull-down current over a long period of time match each other. Thus, the current source is adjusted by using such feedback control that makes the common-mode voltage output constant.
Also, Japanese Unexamined Patent Application Publication No. 2003-347860 discloses a technique for suppressing generation of a common-mode voltage by adjusting the driving timings of drive transistors.